Fluid motor with valve disk and cushioning means



J. c. BENDER 2,539,720 7 FLUID MOTOR WITH VALVE DISK AND CUSHIONING MEANS Jan. 30, 1951 Filed Sept. 10, 1948 2 Sheets-Sheet l d'iflencierw INVENTOR ATTORNEYS Jan. 30, 1951 J. c. BENDEIR FLUID MOTOR WITH VALVE DISK AND CUSHIONING MEANS I Filed Sept. 10, 1948 2 sheets-sheet 2 INVENTOR ATTORNEYS Patented Jan. 30, 1951 UNITED STATES OFFICE FLUID MOTOR WITH VALVE DISK AND CUSHIONING MEANS 2 Claims.

This invention relates to a hydraulic hedge clipper or mower of the reciprocating knife type, adapted to clip hedges, lawns, or the like. In particular, the construction is adapted especially for the clipping of hedges.

An important object of the invention is to provide an improved hydraulic clipper of the character described, wherein the knife action will be smoother, more quiet,-.and less damaging on the parts associated with the knives.

Other important objects of the invention are relatively light, capable of manufacture at comparatively low cost considering the advantages attained thereby, and having a minimum of parts arranged in a manner whereby they will not readily get out of order.

With the foregoing and other objects in view which will appear as the description proceeds, the invention consists of certain novel details of construction and combinations of parts hereinafter more fully described and pointed out in the claims, it being understood that changes may be made in the construction and arrangement of parts without departing from the spirit of the invention as claimed.

Referring to the drawings Figure 1 is a view partly in top plan and partly in longitudinal section, of a hydraulic clipper constructed in accordance with the invention.

Figure 2 is a vertical section through a motor casing embodied in the invention.

Figure 3 is an enlarged longitudinal section through a piston and centering valve arrangement.

Figure 4 is a section on line 44 of Fig. 3.

Figure 5 is a section taken substantially on line 5-5 of Fig. 1.

Figure 6 is a section taken substantially on line 6-6 of Fig. 1.

Referring to the drawings in detail a V belt leading from any suitable motor (not shown) is adapted to power a drive wheel ID, for the purpose of rotating crank shaft 1 l, to which are connected the reciprocating connecting rods I2 carrying pistons l3 that reciprocate in the cylinders M integral with the bottom plate l5 of a fluid casing l6. Said casing i6 is filled with fluid to a suitable level, indicated in the present instance at H. Compensator ports [8 are formed in the respective cylinders M, to permit fluid to flow into or be forced from the cylinders responsive to reciprocation of the pistons l3, and a fluid outlet is provided for each cylinder, said fluid outlet to provide a hydraulic clipper thatwill be durable,

being designated 20. The cylinders are normally closed by means of the 'plugs [9.

Extending from the outlets 20 are the hoses 2| and 22, these being of any suitable length sufficient to permit clipping operations with ease. A plate 23 has cast integrally therewith a generally cylindrical cylinder housing 24, having at its ends the annular flanges or collars 25, adapted to receive the hose couplings 26, whereby the hoses 2i and 22 may be coupled into the respective ends of the cylinder housing 24.

Also formed in the collars 25 of the cylinder or piston housing 2 5 are vent openings in which are positioned the air vent plugs 21.

The piston housing 24 is formed with a smooth walled end to end bore 28, and the ends of this bore are closed by the annularly flanged cylinder heads 29, from the inner surface of which extend the studs 36, whereby the heads 29 can be aligned with the bore 28, and integrally formed with the studs 3% and extending inwardly of the ends of bore 28 are the nipples 3!.

The outer ends of the cylinder heads 29 are formed with the threaded sockets 32, receiving the tightening nuts 33, designed to prevent leakage of fluid from the bore 28 of the piston housing.

Reciprocating in the opposed piston or cylinder heads 29 is the elongated piston rod 34, that projects beyond either end of the cylinder or piston housing 2%, as readily seen from Fig. l.

Referring now to Figs. 3 and 4, there is fixedly secured to the piston rod 34, intermediate the ends of the piston rod, the piston 35, that is pinned to the rod 34 by means of the cross pin 35. Piston 3B is formed as a centrally apertured collar or ring, as readily seen from Fig. 4.

Formed in the marginal portion of the piston head 36 are openings 31, that extend transversely through the piston head, so as to provide communication between the opposite sides thereof. In the present instance, as clearly seen from Fig. 4, four such openings are provided, but this number may be increased or decreased as desired. In any event, there is extended through each opening 31 a tie pin 33, and it may be noted from Figs. 3 and 4 that the openings are of notably greater diameter than the diameter of the tie pin, so as to provide a clearance for the passage of fluid through the openings during reciprocation of the tie pin in the piston head.

To the ends of the tie pin are fixedly secured the opposed valve discs 39, which as seen from Fig. 3, are of slightly less diameter than the diameter of the piston head, so as to provide a clearance between the periphery of the respective By means of clamps 42, the projecting ends of the piston rod 34 are made rigid With.the: upstanding ends 43 of arms 44 that are integralwith the movable knife 45, having teeth 46. Thus, reciprocation of the piston rod 34 reciprocates at high speed the knife 45.

Formed in the knife 45 are elongated slots 41,

through which extend the pins 48, that: also extend through the stationary knife 49 having the teeth 50;. and through the cover plate; 51;, also;

stationary, that is secured to'vthe stationary knife- 49Lby a: plurality. of rivets 52 or similar fastening means- Rivets 52-pass throughend spacer blocks 53 and an. elongated middle spacer block. 55, whereby a. space is defined between the fixedly, connected cover plate and stationar-yknife; within whichspacethe movable knife d-isadapted to be reciprocated.

In operation, it. will be understood that on rotation of the drive wheel It); the. pistons I3 willbe: alternately reci'procated, so that: as fluid. is

forcedthrough hose 21-, it will be withdrawnthrough hose 22,, and vice versa. Thus, theifluid.

is2forc8d under pressure into one. end' of the bore 28-,while' beingwithdrawnfrom the other end- As a result, andassuming that fluid isiabout to beforced. through the hose 22-, considering the position of the partsin Fig. 1;.itwil1 be observed:

that said fluid will flow around the nipple 31' at the right. of the piston housing 24, and willbe: forced under pressure againstthe outer surface of' the; right: hand" valve disc 39. As a. result, the pistonhead' 36 will-be forcedto'the-left'in Fig; 1'. As soon asv the left hand valve; disc 39- comes against: the left nipple 31, the fluid, still exerting force toward the left, bears uponthe peripheral portion of the: piston head 36-, and. continues to force it to the left, although the. two valve. discs 39 will of course now be stationary. As'the piston head. 36 begins this lastv movement'- between the valve disc 39', fluid moving through thecl'earance openings 31' and 4! will cushion the final impact of the piston head.

This operation will result when the-pistonhead moves to the right, back to the position illustrat 4 ed in Fig. 1. Thus, rapid reciprocation of the movable knife 45 is obtained, and it may be noted that at the very end of the travel of the movable knife in either direction, the movement is slowed imperceptibly, to relieve impact upon the parts which would otherwise result.

What is claimed is:

1. In a fluid motor a cylinder havin closed ends; means at" opposite ends of the cylinder for forcing fluid into said opposite ends alternately; a piston mounted for reciprocation within said cylinder under pressure of said fluid, said piston having ports extending therethrough; and valve discs mounted on opposite faces of said piston and alternately closing said ports, said valve discs adapted tobe opened by contact with the end walls of. the. cylinder for cushioning the blow of the piston against said end walls.

2.. In a fluid motor a cylinder having closed ends; means for forcing fluid into said cylinder, said; means' adapted to alternate said fluid. pres sure: betweensaid; ends of the cylinder; a piston mounted for slidable reciprocation within said cylinder under pressureof the fluid forced thereinto, said piston having a snug wiping fit against the wall of-theey'linder and having ports formed therein; valve discs mountedon' opposite faces of said piston, saidvalve discs bein of substantially less; diameter than the diameter of the piston to provide clearance spaces between the peripheries of the. valve. discsandthe wall of the cylinder, said, discs a-dapt'ed to close the ports of the piston whenlforced.against the face of the piston; and rods rigidly connecting said valve discs and slidable, in. the. piston, whereby as the piston will approach one-end; of the cylinder the valve disc on one face of the piston-will be engaged by the cylinder end for forcing. the opposite valve disc out of port. closing position for passage of fluid throughv thepiston to cushion the blow of said p ston.

JOHN C. BENDER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 531,792 Forslund et' al. Jan. 1,1895 840 ,886 Wilkins Jan. 8, 1907 845,827 Steedman- Mar. 5, 1907 1,814,649 Wade July 14, 1931 1,939,851 Horste Dec. 19, 1933 2,493,602 Sterrett Jan. 3,1950 

